Republican lawmakers are calling for a full investigation into the Internal Revenue Service after a top official revealed Friday that the agency specifically flagged tea party and conservative groups for review to see if they were violating their tax-exempt status.

Several Republicans voiced suspicion last year that the IRS was unduly focused on conservative groups, after several groups reported that they had been asked to fill out extensive amounts of paper work and go to great lengths to prove they were not violating their tax-exempt status.

Earlier today, ahead of a report by the inspector general for tax administration, the IRS admitted that it had targeted conservative groups for additional reviews, with an eye toward catching violations of tax-exempt status. Groups were singled out based on keywords such as “patriot” and “tea party” in their tax-exempt status applications, according to Lois G. Lerner, the IRS’s director of tax-exempt organizations.

House Oversight Committee Chairman Darrell Issa and Rep. Jim Jordan sent a letter to the inspector general in June 2012 asking that the committee be provided with “periodic updates” on the investigation into whether the IRS was applying an inappropriate level of scrutiny to such groups.

“The Committee will aggressively follow up on the IG report and hold responsible officials accountable for this political retaliation,” reads a new statement on the oversight committee’s web site. A representative from the committee confirmed to The Daily Caller that this would include hearings, but did not give a time or schedule.

Senate Minority Leader Mitch McConnell addressed the issue in a speech at the American Enterprise Institute also in June.

“Let’s be very clear: no individual or group in this country should have to face harassment or intimidation, or incur crippling expenses, defending themselves against their own government, simply because that government doesn’t like the message they’re advocating,” he said at the time.

Almost a full year later, McConnell is now among those calling for an investigation into the IRS and how such political targeting was allowed to happen.

In a statement Friday, McConnell blasted the administration for “political thuggery” and called “on the White House to conduct a transparent, government-wide review aimed at assuring the American people that these thuggish practices are not underway at the IRS or everywhere in the administration against anyone, regardless of their political views.”

“[M]ake no mistake, an apology won’t put this issue to rest,” he added. “Now more than ever we need to send a clear message to the Obama Administration that the First Amendment is non-negotiable, and that apologies after an election year are not a sufficient response to what we now know took place at the IRS. This kind of political thuggery has absolutely no place in our politics.”

House Majority Leader Eric Cantor vowed in a statement that “The House will investigate this matter,” and Issa promised his committee would “aggressively follow up” on the report.

“The fact that Americans were targeted by the IRS because of their political beliefs is unconscionable. The Committee will aggressively follow up on the IG report and hold responsible officials accountable for this political retaliation,” he said in a statement.

Rep. Charles Boustany, Chairman of the Ways and Means Subcommittee on Oversight, sent a letter to Steve Miller, the acting commissioner of the IRS, Friday requesting “all communications containing the words ‘tea party,’ ‘patriot,’ or ‘conservative,’” terms that the IRS official said they used to flag groups, and “Names and titles of all individuals involved in this discrimination.”

Boustany noted in a statement that his subcommittee has been pursuing an inquiry into the issue since last year, and had not received cooperation from the IRS.

“The IRS’s ‘too little too late’ response is unacceptable, and I will continue to work to ensure there are protections in place so no American, regardless of political affiliation, has their right to free speech threatened by the IRS,” he said.

Speaker of the House John Boehner said he would support such an investigation, applauding Boustany, Jordan and Issa for taking the lead on the issue, and saying he “strongly” supported McConnell’s call for an investigation.

“Today, we are left with serious questions: who is ultimately responsible for this travesty? What actions will the Obama administration take to hold them accountable? And have other federal agencies used government powers to attack Americans for partisan reasons?” Boehner asked.

The Republican National Committee joined the calls for an investigation, sending a letter to Boehner and Senate Majority Leader Harry Reid and asking for an investigation.

“There’s no explanation for singling out groups based on their political views—except for blatant political opportunism. It’s an obvious abuse of power and nothing less than government corruption,” said RNC Chair Reince Priebus in a statement.

“Today, I’m asking Speaker Boehner and Leader Reid for their support in calling for an immediate investigation and congressional hearings. It will take more than a weak apology from the IRS to regain the public’s trust.”